package nautilus.lab.activity;

/*
Note: these not exist or not work before Android 2.3

GLES20.glVertexAttribPointer
GLES20.glDrawElements
 */

import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.app.Activity;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
import android.os.Bundle;
import android.util.Log;


public class GLES20VBOTest extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        GLSurfaceView view = new GLSurfaceView(this);
        view.setEGLContextClientVersion(2);
        view.setRenderer(new GDC11Renderer());

        setContentView(view);
    }

}

// Helper class to create some different geometries
class GeoData {

    public float[] mVertices;
    public short[] mIndices;

    private GeoData() {}

    static public GeoData halfpipe() {
        GeoData creator = new GeoData();
        creator.mVertices = createVertices1(44);
        creator.mIndices = createIndices1(44);
        return creator;
    }

    static public GeoData circle() {
        GeoData creator = new GeoData();
        creator.mVertices = createVertices2(32);
        creator.mIndices = createIndices2(32);
        return creator;
    }

    static public GeoData grid() {
        GeoData creator = new GeoData();
        creator.mVertices = createGridVertices(30,30);
        creator.mIndices = createGridIndices(30,30);
        return creator;
    }

    static float[] createGridVertices(int m, int n) {
        float[] vertices = new float[3*(2*m + 2*n + 4)];

        float y = 0.1f;
        float S = 2.8f;
        for (int i=0; i<=m; i++) {
            float x = S*(float) (-0.5 + (1.0*i)/m);
            float z = S*0.5f;
            vertices[6*i + 0] = x;
            vertices[6*i + 1] = y;
            vertices[6*i + 2] = z;
            vertices[6*i + 3] = x;
            vertices[6*i + 4] = y;
            vertices[6*i + 5] = -z;
        }

        int start = 3*(2*m + 2);
        // start = 0;
        for (int i=0; i<=n; i++) {
            float z = S*(float) (-0.5 + (1.0*i)/n);
            float x = S*0.5f;
            vertices[start + 6*i + 0] = x;
            vertices[start + 6*i + 1] = y;
            vertices[start + 6*i + 2] = z;
            vertices[start + 6*i + 3] = -x;
            vertices[start + 6*i + 4] = y;
            vertices[start + 6*i + 5] = z;
        }

        float[] M = new float[16];
        Matrix.setIdentityM(M, 0);
        Matrix.rotateM(M, 0, 27, 0.76f, -0.9f, 1.5f);
        int count = (2*m + 2*n + 4);
        Log.d("MKZ", "A: " + count);
        Log.d("MKZ", "B: " + vertices.length / 3);
        for (int i=0; i<count-1; i++) {
            int offset = 3*i;
            Log.d("MKZ", "offset: " + offset);
            Matrix.multiplyMV(vertices, offset, M, 0, vertices, offset);
        }

        return vertices;
    }

    static short[] createGridIndices(int m, int n) {
        int N = 2*(m+n+2);
        short[] indices = new short[N];
        for (int i=0; i<N; i++) {
            indices[i] = (short)i;
        }
        return indices;
    }

    static float[] createVertices1(int n) {
        int NUM_COMPONENTS = 6;
        float S = 0.75f;
        float X = 1f;
        float z0 = 1.3f;
        float z1 = 1.1f;
        float dx = 2*X / n;
        float[] vertices = new float[NUM_COMPONENTS*(n+1)*2];
        for (int i=0; i<(n+1); i++) {
            int I0 = 2*NUM_COMPONENTS*i;
            int I1 = 2*NUM_COMPONENTS*i + NUM_COMPONENTS;
            float x = -X + dx*i;
            float y = -(float) Math.sqrt(1.0 - x*x);
            vertices[I0 + 0] = S*x;
            vertices[I0 + 1] = S*y;
            vertices[I0 + 2] = S*z0;
            vertices[I0 + 3] = x;
            vertices[I0 + 4] = y;
            vertices[I0 + 5] = 0;

            vertices[I1 + 0] = S*x; 
            vertices[I1 + 1] = S*y;
            vertices[I1 + 2] = S*z1;
            vertices[I1 + 3] = x;
            vertices[I1 + 4] = y;
            vertices[I1 + 5] = 0;
        }
        return vertices;
    }
    static short[] createIndices1(int n) {
        short[] indices = new short[(n+1)*2];
        for (short i=0; i<(n+1)*2; i++) {
            indices[i] = i;
        }
        return indices;
    }

    static float[] createVertices2(int n) {
        int NUM_COMPONENTS = 6;
        float[] vertices = new float[NUM_COMPONENTS*(n+2)];
        final float S = 0.9f;
        final float Y = -0.0f;
        vertices[0] = 0;
        vertices[1] = Y;
        vertices[2] = 0;
        vertices[3] = 0;
        vertices[4] =-1;
        vertices[5] = 0;
        for (int i=0; i<=n; i++) {
            int I = 6 + 6*i;
            float a = (float) (0.75*2*Math.PI*i/n);
            float x = (float) (S*Math.cos(a));
            float z = (float) (S*Math.sin(a));
            vertices[I+0] = x;
            vertices[I+1] = Y;
            vertices[I+2] = z;
            vertices[I+3] = 0;
            vertices[I+4] =-1;
            vertices[I+5] = 0;
        }
        return vertices;
    }
    static short[] createIndices2(int n) {
        short[] indices = new short[(n+2)];
        for (short i=0; i<(n+2); i++) {
            indices[i] = i;
        }
        return indices;
    }
}

// all GLES20 calls are made here
class Shader {
    // THESE ARE ARBITRARY VALUES, the only constraints are
    // - must be different
    // - must be less than a maximum value
    static final int VERTEX_POS = 3;
    static final int NORMAL_POS = 4;
    static final int TEX_POS = 5;
    static final String TAG = "VBOTest";

    private int mProgramId;
    private int mViewProjectionLoc;
    private int mLightVectorLoc;
    private int mColorLoc;
    private int mEnableLightLoc;


    Shader() {
        mProgramId = loadProgram(kVertexShader, kFragmentShader);
        GLES20.glBindAttribLocation(mProgramId, Shader.VERTEX_POS, "position");
        GLES20.glBindAttribLocation(mProgramId, Shader.NORMAL_POS, "normal");
        GLES20.glLinkProgram(mProgramId);
        mViewProjectionLoc =
            GLES20.glGetUniformLocation(mProgramId, "worldViewProjection");
        mLightVectorLoc =
            GLES20.glGetUniformLocation(mProgramId, "lightVector");
        mColorLoc =
            GLES20.glGetUniformLocation(mProgramId, "color");
        mEnableLightLoc =
            GLES20.glGetUniformLocation(mProgramId, "enableLight");

        // Other state.
        GLES20.glClearColor(0.7f, 0.7f, 0.7f, 1.0f);
        GLES20.glEnable(GLES20.GL_CULL_FACE);
        GLES20.glEnable(GLES20.GL_DEPTH_TEST);
    }

    public void use() {
        GLES20.glUseProgram(mProgramId);
    }
    public void setCamera(float[] viewProjectionMatrix) {
        GLES20.glUniformMatrix4fv(mViewProjectionLoc,
                1,
                false, // transpose isn't supported
                viewProjectionMatrix, 0);
    }
    public void setLight(float[] transformedLightVector) {
        GLES20.glUniform3fv(mLightVectorLoc, 1, transformedLightVector, 0);
    }
    public void setColor(float[] color) {
        GLES20.glUniform3fv(mColorLoc, 1, color, 0);
    }
    public void enableLight(boolean val) {
        GLES20.glUniform1i(mEnableLightLoc, val ? 1 : 0);
    }

    static public void setViewPort(int width, int height) {
        GLES20.glViewport(0, 0, width, height);
    }



    private static String kLogTag = "GDC11";

    private static int getShader(String source, int type) {
        int shader = GLES20.glCreateShader(type);
        if (shader == 0) return 0;

        GLES20.glShaderSource(shader, source);
        GLES20.glCompileShader(shader);
        int[] compiled = { 0 };
        GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compiled, 0);
        if (compiled[0] == 0) {
            Log.e(kLogTag, GLES20.glGetShaderInfoLog(shader));
        }
        return shader;
    }

    public static int loadProgram(String vertexShader,
            String fragmentShader) {
        int vs = getShader(vertexShader, GLES20.GL_VERTEX_SHADER);
        int fs = getShader(fragmentShader, GLES20.GL_FRAGMENT_SHADER);
        if (vs == 0 || fs == 0) return 0;

        int program = GLES20.glCreateProgram();
        GLES20.glAttachShader(program, vs);
        GLES20.glAttachShader(program, fs);
        GLES20.glLinkProgram(program);

        int[] linked = { 0 };
        GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linked, 0);
        if (linked[0] == 0) {
            Log.e(kLogTag, GLES20.glGetProgramInfoLog(program));
            return 0;
        }
        return program;
    }


    private static final String kVertexShader =
        "precision mediump float;                                   \n" +
        "uniform mat4 worldViewProjection;                          \n" +
        "uniform vec3 lightVector;                                  \n" +
        "attribute vec3 position;                                   \n" +
        "attribute vec3 normal;                                     \n" +
        "varying float light;                                       \n" +
        "void main() {                                              \n" +
        // |lightVector| is in the model space, so the model
        // doesn't have to be transformed.
        "  light = max(dot(normal, lightVector), 0.0) + 0.2;        \n" +
        "  gl_Position = worldViewProjection * vec4(position, 1.0); \n" +
        "}";

    private static final String kFragmentShader =
        "precision mediump float;                                   \n" +
        "uniform sampler2D textureSampler;                          \n" +
        "uniform vec3 color;                                        \n" +
        "uniform int enableLight;                                   \n" +
        "varying float light;                                       \n" +
        "void main() {                                              \n" +
        "  if (1 == enableLight) {                                  \n" +
        "    gl_FragColor = light * vec4(color,1);                  \n" +
        "  } else {                                                 \n" +
        "    gl_FragColor = vec4(color,1);                          \n" +
        "  }                                                        \n" +
        // "  gl_FragColor = light * vec4(0.1,0.7,0.0,1);               \n" +
        "}";


    public void clearView() {
        int clearMask = GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT;
        GLES20.glClear(clearMask);
    }
}

// view matrices
class Camera {
    private float mPhi, mZ = 3.5f;
    private float[] mProjectionMatrix = new float[16];
    private float[] mViewMatrix = new float[16];
    private float[] mViewProjectionMatrix = new float[16];


    // Updates mViewProjectionMatrix with the current camera position.
    public void updateMatrices() {
        Matrix.setIdentityM(mViewMatrix, 0);
        Matrix.translateM(mViewMatrix, 0, 0, 0, -mZ);
        Matrix.rotateM(mViewMatrix, 0, mPhi, 0, 1, 0);
        Matrix.rotateM(mViewMatrix, 0, -90, 1, 0, 0);
        Matrix.multiplyMM(
                mViewProjectionMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0);
    }

    public float[] viewMatrix() {
        return mViewMatrix;
    }

    public void perspective(int width, int height) {
        float aspect = width / (float)height;
        perspectiveM(
                mProjectionMatrix,
                (float)Math.toRadians(45),
                aspect, 0.1f, 15.f);
        // aspect, 0.5f, 5.f);
        updateMatrices();
    }

    // Like gluPerspective(), but writes the output to a Matrix.
    static private void perspectiveM(
            float[] m, float angle, float aspect, float near, float far) {
        float f = (float)Math.tan(0.5 * (Math.PI - angle));
        float range = near - far;

        m[0] = f / aspect;
        m[1] = 0;
        m[2] = 0;
        m[3] = 0;

        m[4] = 0;
        m[5] = f;
        m[6] = 0;
        m[7] = 0;

        m[8] = 0;
        m[9] = 0; 
        m[10] = far / range;
        m[11] = -1;

        m[12] = 0;
        m[13] = 0;
        m[14] = near * far / range;
        m[15] = 0;
    }

    public void use(Shader shader) {
        shader.setCamera(mViewProjectionMatrix);
    }
}

// The renderer object.
// Manages the graphic view / content
class GDC11Renderer implements GLSurfaceView.Renderer {

    // OpenGL state stuff.
    private Shader mShader;
    private Camera mCamera;

    VBO mVBO1, mVBO2, mVBO3;

    private float[] mLightVector = { 2/3.f, 1/3.f, 2/3.f };  // Needs to be normalized
    private float[] mTransformedLightVector = new float[3];

    private void updateLightVector() {

        // Transform the light vector into model space. Since mViewMatrix
        // is orthogonal, the reverse transform can be done by multiplying
        // with the transpose.

        float[] viewMatrix = mCamera.viewMatrix();

        mTransformedLightVector[0] =
            viewMatrix[0] * mLightVector[0] +
            viewMatrix[1] * mLightVector[1] +
            viewMatrix[2] * mLightVector[2];
        mTransformedLightVector[1] =
            viewMatrix[4] * mLightVector[0] +
            viewMatrix[5] * mLightVector[1] +
            viewMatrix[6] * mLightVector[2];
        mTransformedLightVector[2] =
            viewMatrix[8] * mLightVector[0] +
            viewMatrix[9] * mLightVector[1] +
            viewMatrix[10] * mLightVector[2];            
    }

    // This is called continuously to render.
    @Override
    public void onDrawFrame(GL10 unused) {

        mShader.use();
        mShader.clearView();
        mCamera.use(mShader);
        mShader.setLight(mTransformedLightVector);

        // VBO
        mShader.enableLight(true);

        mShader.setColor(red);
        mVBO1.draw();

        mShader.setColor(gold);
        mVBO2.draw();

        mShader.enableLight(false);
        mShader.setColor(brown);
        mVBO3.draw();

    }
    static float[] green = {0.2f,1,0.2f};
    static float[] brown = {0.7f,0.4f,0.2f};
    static float[] red = {0.9f,0,0};
    static float[] gold = {0.9f,0.8f,0.1f};
    static float[] black = {0,0,0};


    @Override
    public void onSurfaceCreated(GL10 unused, EGLConfig config) {
        // CREATE GEOMETRY
        // NEVER load stuff on the render thread in real life!
        // You'd call fc.map() and b.load() on a loader thread, and
        // only then upload that to GL once it's done.

        mShader = new Shader();
        mCamera = new Camera();

        GeoData data = GeoData.halfpipe();
        mVBO1 = new VBO(data.mVertices, data.mIndices, GLES20.GL_TRIANGLE_STRIP, true, false, -1);

        data = GeoData.circle();
        mVBO2 = new VBO(data.mVertices, data.mIndices, GLES20.GL_TRIANGLE_FAN, true, false, -1);

        data = GeoData.grid();
        mVBO3 = new VBO(data.mVertices, data.mIndices, GLES20.GL_LINES, false, false, -1);
    }

    // This is called when the surface changes, e.g. after screen rotation.
    @Override
    public void onSurfaceChanged(GL10 unused, int width, int height) {
        mCamera.perspective(width, height);

        updateLightVector();

        // Necessary if the manifest contains |android:configChanges="orientation"|.
        Shader.setViewPort(width, height);
    }
}


class VBO {
    int mNumIndices;

    int mIndexBufferId; 
    int mVertexBufferId;
    boolean mUseNormals;
    boolean mUseTexCoords;

    int mType;
    int mNumComponents;
    int mStride;

    VBO(float[] vertices,               // array of vertex data
            short[] indices,            // indices
            int type,                   // GL_POINTS, GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES,
            // GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, and GL_TRIANGLES
            boolean vertexNormals,      // normals used ?
            boolean vertexTexCoords,    // texCoords used ?
            int stride) {               // struct size in bytes; if stride <= 0 -> stride will be calculated


        mType = type;
        mUseNormals = vertexNormals;
        mUseTexCoords = vertexTexCoords;

        mNumComponents = 3;
        if (mUseNormals) {
            mNumComponents += 3;
        }
        if (mUseTexCoords) {
            mNumComponents += 2;
        }

        if (stride <= 0) {
            mStride = 4 * mNumComponents;
        } else {
            mStride = stride;
        }

        int[] buffers = {0,0};
        GLES20.glGenBuffers(2, buffers, 0);

        mVertexBufferId = buffers[0];
        mIndexBufferId = buffers[1];

        createVertexBuffer(GLES20.GL_ARRAY_BUFFER, vertices, mVertexBufferId);
        createIndexBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, indices, mIndexBufferId);
        mNumIndices = indices.length;
    }

    void deleteBuffers() {
        int[] buffers = {mVertexBufferId, mIndexBufferId};
        GLES20.glDeleteBuffers(2, buffers, 0);
        mVertexBufferId = 0;
        mIndexBufferId = 0;
    }

    void draw() {
        if (0 == mVertexBufferId) {
            return;
        }
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mVertexBufferId);

        GLES20.glEnableVertexAttribArray(Shader.VERTEX_POS);
        if (mUseNormals) {
            GLES20.glEnableVertexAttribArray(Shader.NORMAL_POS);
        }
        if (mUseTexCoords) {
            GLES20.glEnableVertexAttribArray(Shader.TEX_POS);
        }

        int offset = 0;

        GLES20.glVertexAttribPointer(
                Shader.VERTEX_POS,      // generic id
                3,                      // vertex has 3 components
                GLES20.GL_FLOAT,        // data type
                false,                  // no normalizing
                mStride,                // stride: sizeof(float) * number of components
                offset);                // offset 0; vertex starts at zero
        offset += 4 * 3;

        if (mUseNormals) {

            GLES20.glVertexAttribPointer(
                    Shader.NORMAL_POS,
                    3,
                    GLES20.GL_FLOAT,
                    false,
                    mStride,
                    offset);
            offset += 4 * 3;
        }

        if (mUseTexCoords) {

            GLES20.glVertexAttribPointer(
                    Shader.TEX_POS,
                    2,                      // texCoord has 2 components
                    GLES20.GL_FLOAT,
                    false,
                    mStride,
                    offset);
            offset += 4 * 3;
        }

        GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, mIndexBufferId);
        GLES20.glDrawElements(mType, mNumIndices, GLES20.GL_UNSIGNED_SHORT, 0);

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
        GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);

        GLES20.glDisableVertexAttribArray(Shader.VERTEX_POS);
        GLES20.glDisableVertexAttribArray(Shader.NORMAL_POS);
        GLES20.glDisableVertexAttribArray(Shader.TEX_POS);
    }
    static void createVertexBuffer(int target, float[] vertices, int bufferId) {
        int size = vertices.length * 4;
        FloatBuffer fb = ByteBuffer.allocateDirect(4*vertices.length).order(ByteOrder.nativeOrder()).asFloatBuffer();
        fb.put(vertices);
        fb.position(0);

        createBuffer(target, fb, size, bufferId);
    }
    static void createIndexBuffer(int target, short[] indices, int bufferId) {
        int size = indices.length * 2;
        ShortBuffer sb = ByteBuffer.allocateDirect(size).order(ByteOrder.nativeOrder()).asShortBuffer();
        sb.put(indices);
        sb.position(0);

        createBuffer(target, sb, size, bufferId);
    }
    static void createBuffer(int target, Buffer buf, int size, int bufferId) {
        GLES20.glBindBuffer(target, bufferId);
        GLES20.glBufferData(target, size, buf, GLES20.GL_STATIC_DRAW);
        GLES20.glBindBuffer(target, 0);
    }
}